We have devised a technique that will greatly simplify and make cost effective the fabrication of dense silicone fibers for use in gas exchange applications including long-term extracorporeal life support, implantable artificial lung, and other cardiorespiratory procedures. The technique allows for producing, non-porous, high performing, and economically attractive compact gas exchange devices, analogous to their microporous membrane hollow fibers (MMHF) counterparts. Devices incorporating MMHF have become popular mainly because of enhanced gas exchange due to the convective mixing induced by blood flowing over thousands of tiny hollow fibers. This property allows for designing highly efficient gas exchange devices in relatively compact volumes. Yet MMHF suffer from fowling, and plasma leakage when they are used for extended periods of time, and from propensity to gas embolization when the gas side pressure exceeds the blood side pressure. Thus incorporating the compactness and effectiveness of hollow fibers configuration with the ability of solid silicone membranes to withstanding plasma leakage and gas embolization are desirable properties in a membrane designed blood oxygenation. In Phase 1 we propose to further develop the fabrication technique and to evaluate the gas exchange and hemodynamic performance of the dense hollow fibers incorporated in prototype as exchange devices. PROPOSED COMMERCIAL APPLICATION: In the US alone over 750,000 patients a year receive some form of cardiorespiratory support requring gas exchange devices. The present device will eliminate the possibility of plasma leakage and gas embolization which are possible in microporous membrane oxygenators.